Lighting unit



H. HELMHOLZ LIGHTING UNIT June 2, 1964 2 Sheets-Sheet 1 Filed July 12, 1961 an n m :IP. b H a w A M a m w m b :n m

June 2, 1964 Filed July 12, 1961 114a 1131; fi m "3b H. HELMHOLZ LIGHTING UNIT 2 SheetsSheet 2 Fig. 5

KT 2 1a W 216 4a 217 LIB United States Patent 3,135,472 LEGHTZNG UNIT ela, Frankfurt am Main, Germany, assignnr holz fa lauli, ileleuchtungstechnische Speaialr, ranlrfurt am lviain, Germany Filed July 12, l9til, Ser. No. 123,569 Claims prierity, application Germany duly l5,

Claims. {@l. Zen 7$) Hurst lie tribution of light than the grillworks of which I am aware at this time.

Another object of the invention is to provide a grill- Work of the just outlined characteristics which is easy to clean, which is of eye-'Jleasing'appearance, which may be produced in any desired size and/or shape, which may be manufactured at a low cost and of a variety of readily available materials, which may be constructed and assembled in such a way as to deflect the light rays in a selected direction, and which may be produced with substantial savings in material as compared with the material requirements of conventional grillworks. H

A further object of the instant invention is to provide a novel lighting unit which embodies a grillwork of the above outlined characteristics.

Still another object of my invention is to provide a lighting unit embodying a grillwork which is constructed and assembled in such away that the illuminating effect is the same in the longitudinal and transverse directions of the unit.

A concomitant object of the present invention is to provide a grillwork for use in artificial illumination-of homes and public buildings which is capable of redirecting light more effectively into useful zones of the area to be lighted and of shielding the eyes from direct view of the light source, whose light reflecting and directing components may be manufactured in many desired colors, sizes and/or shapes, which insures freedom from glare so thattthe lighting system is comfortable throughout prolonged work periods even to persons standing or seated near to direct line of sight to the light source, and which may be manufactured in many sizes and shapes to constitute an advantageous and highly superior substitute for conventional grillworks.

With the above objects in view, theinvention resides in the provision of a grillwork which is utilized for modifying the distribution of light emanating from a light source and which comprises a plurality of separate (i.e. unconnected) corrugated louvers made of a metallic, synthetic plastic, vitreous 'orvpaper like material and defining between themselves one or more'continuous channels for the passage of light rays from a light source located 'at one side of the grillwork. The strip like louvers'may assume an undulate, zig-zag, trapeziform or other'shape which is obtained by deforming adjacent sections of the louvers in opposite directions. The channels are preferably of uniform or nearly uniform width throughout the'full length thereof. The'individual louvers may enclose right, obtuse oracute' angles with the general plane t the grillworlr, and the light source may. assume the form of one or more tubular fluorescent lamps, of an Fatented June 2, 1964 illuminated surface such as the ceiling of an office, or the like. Owing to the corrugated shape of the louvers and of the channels therebetween, the grillwork reduces or eliminates glare and conceals the light source to the eye of an observer. The grillwork and the light source may be mounted in a common frame or housing to form a lighting unit, also called luminaire.

The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following detailed'description of certain specific embodiments with reference to the accompanying drawings, in which:

FIG. 1 is a bottom plan view of a lighting unit or luminaire including a grillwork which embodies one form of my invention and whose undulate louvers enclose right angles with the general planeof the grillwork;

FIG. 2 is a longitudinal section through the lighting unit as seen in the direction of arrows from the line IIII of FIG. 1;

FIG. 3 is a transverse section through the lighting unit as seen in the direction of arrows from the line IIIIII of PEG. 1; p

FIG. 4 is a bottom plan view of a grillwork comprising zig-zag shaped louvers whose sections enclose obtuse angles with each other;

Fit 5 is a bottom plan view of a square grillwork {hose louvers resemble undamped high-amplitude waves;

FIG. 6 is a bottom plan view of a square grillwork whose louvers resemble the louvers shown in FIG. 4 excepting that the louver sections enclose right angles with each other;

FIG. 7 is a bottom plan view of a grillwork comprising a plurality of trapeziform louvers;

FIG. 8 is a bottom plan view of a grillwork which is mounted in a square frame and whose undulate louvers extenddiagonally with respect to the frame;

FIG; 9 is a transverse section through a'lightingunit whose louvers are inclined through acute angles with respect to the general plane of the grillwork; and I FIG. 10 is a bottom plan view of a modified lighting unit.

Referring now in greater detail to the illustrated embodiments, and first to FIGS. 1 to 3, there is shown a lighting unit or luminaire A comprising a rectangular frame or housing 18 which defines an internal compart ment 16a for a source of light including two elongated tubular lamps Ha, llb'which are parallel with the longitudinal extension of the frame and which are mounted in pairwise arranged sockets 12 secured to the end walls of the frame." "The lamps flla, 1112 may assume the form of known low-voltage fluorescent lamps whichare avail able in a variety-of lengths and diameters. 1

The underside of the frame 10 is formed with an 'eloh} gated rectangular-opening which accommodates a grill work comprising a plurality of elongated corrugated louvers or strips 13-16 made of a metallic, plastic, vitreous or paper like material. I

a The louvers i3- 16 are of undulate shape i.e. they assume the form of undamped sinewaves, and they define between themselves a plurality of continuous'corrugate'd, i.e. undulate, channels 13 which extend in the longitudinal direction of the lamps'lla, 11b and whose Width is uniform or at least nearly uniform throughout the full tending louvers Zila and a plurality of straight, transversely -13 extending louvers 20b. It will be noted that the improved grillwork dispenses with transversely extending louvers thus producing savings in material amounting to percent or more despite the fact that the corrugated louvers 13-16 require more material than the straight louvers 20a. In addition, the illuminating effect or efficiency of the improved grillwork is much higher than the efiiciency of the grillwork 20. Furthermore, since the louvers 13-16 define continuous channels 18 which are not interrupted by transversely extending louvers, the improved grillwork may be cleaned with greater ease because a broom, mop, dust cloth, sponge or a like cleaning implement may be introduced from below into each downwardly open channel and may be moved throughout the full length thereof so as to simultaneously remove impurities from the surfaces of two louvers which bound the respective. channel. As a matter of fact, if the improved grillwork is suspended on the ceiling, i.e., if the grillwork is located beneath an overhead source of light, a person standing therebeneath may reach and clean the louvers 13-16 with a mop or broom while standing on the floor so that say a charwoman or a housewife can clean the grillwork at frequent intervals because she can reach the luminaire without being compelled to climb on chairs, tables, ladders or the like. This also insures that the efficiency of the grillwork remains high because the louvers may be cleaned as soon and as frequently as the grillwork exhibits slightest signs of dust, soot or other impurities.

An additional important advantage of a grillwork consisting of corrugated louvers is that it does not produce pronounced shadows such as develop when the light rays are reflected in sharp corners formed by interesecting longitudinal and transverse louvers 20a, 20b of the type indicated in FIG. 1. In other words, the grillwork of my invention produces an illumination which is free of pronounced shadows or light contrasts because the corrugated louvers insure a more uniform distribution of refiected light rays.

Referring back to FIG. 1, it will be noted that the troughs 13b of the undamped wave like first louver 13 are disposed in a common plane with the crests 14a of the adjacent second louver 14, that the troughs 14b of the louver 14 are disposed in a common plane with the crests 15a of the third louver 15, and so forth. In fact, it is often preferred to arrange the louvers in the manner shown in FIG. 10, namely in such a way that the crests 14a actually extend beyond the common plane of the troughs 13b, i.e. into the space defined by the concave portions of the louver 13 between each pair of adjacent troughs 13a.

If the louvers 13-16 are spaced in a manner as shown in FIG. 1, the concave and convex portions or sections of the louvers will fully conceal the light source 11a, 11b to a person observing the lighting unit in the longitudinal direction of the louvers and at an angle inclined through about (see FIG. 2) with respect to the general plane of the grillwork. As indicated in FIG. 3, the spacing between the adjacent louvers may be such that the light source 11a, 11b is concealed to a person looking at the lighting unit in a direction transversely of the louvers and at an angle of about 30 with respect to the general plane of the grillwork.

Of course, the improved lighting unit may comprise different sources of light, eg the entire ceiling may be used as a luminous surface or the ceiling may be illuminated by uniformly or differently spaced incandescent lamps or the like.

FIG. 4 illustrates an elongated rectangular frame 110 which supports the ends of corrugated louvers in the form of zig-zag strips 113-116 each consisting of mutually inclined straight sections. These louvers define between themselves continuous'zig-zag shaped channels 118 which extend throughout the full length of the frame 110. As in the embodiment of FIG. 1, the troughs or lowermost points 113b of the louver 113 are disposed in a common plane with the crests or highermost points 114a of the adjacent second louver 114,.and so forth. The adjacent sections of each louver shown in FIG. 4 enclose between themselves obtuse angles which may but need not substantially exceed The effect of the grillworks shown in FIGS. 1 and 4 is substantially the same, and the decorator, the illuminating engineer or the manufacturer will select that grillwork which is more in conformity with the furnishings in the area in which the lighting unit is installed, which may be manufactured at a lower cost wth the equipment at hand, or which can be produced at a lower cost from a specific material.

If the lighting unit of FIG. 1 or 4 is rather close to the heads of persons who occupy the illuminated area, the spacing between the adjacent louvers 13-16 or 113-116 is rather small to avoid glare. However, the spacing between the louvers may be increased if the lighting unit is installed at a lesser distance from the floor. Additional control of the glare may be achieved by changing the width of the louvers 13-16 or 113-116, by changing the light source, or by changing the distance between the light source and the grillwork.

Referring to FIG. 5, there is shown a grillwork consisting of corrugated louvers 213-217 whose ends are connected to opposite sides of a square frame 210. The adjacent louvers again define between themselves a plurality of continuous undulate channels 218 for the passage of light rays from the non-illustrated light source.

The grillwork of FIG. 5 is of particular advantage as a superior substitute for conventional grillworks whose longitudinally and transversely extending louvers or strips define square interstices or cells. The amplitude of the undulate louvers 213-217 is higher than the amplitude of the louvers 13-16 or the wavelength of the louvers 213-217 is less than the wavelength of louvers 13-16 so that the louvers 213216 insure uniform distribution of light in both main directions because each thereof is similar in outline to the outline of an ordinary rack having square teeth whose corners are rounded off. The width of the channels 218 is not as uniform as in FIG. 1 or 4. It will be noted that the troughs of the louver 213 are coplanar with the crests of the louver 214,. and so forth.

FIG. 6 shows a grillwork consisting of corrugated louvers 313-317 of zig-zag shape whose ends are connected to two parallel sides of a square frame 310. It will be noted that the adjacent oppositely inclined sections of each louver enclose between themselves angles of about 90 degrees, i.e. that the adjacent sections extend diagonally of the frame 310 but alternately enclose angles of +45 and 45 with the longitudinal direction of the respective louver. Such construction of the grillwork produces an effect as described in connection with FIG. 5, i.e. the illumination is the same longitudinally and transversely of the lighting unit. The zig-Zag shaped channels 318 are of uniform width.

FIG. 7 shows a grillwork which consists of corrugated substantially trapeziform louvers 413-416 having ends connected to an elongated rectangular frame 410 and defining between themselves continuous channels 418 whose width varies slightly between the inclined and longitudinally extending sections of the adjacent louvers.

In FIG. 8, the grillwork comprises a plurality of uniformly spaced corrugated louvers 513, 514, 515, 516, 517 517x which are disposed substantially diagonally in a square frame 510. The relative positions of the adjacent louvers are similar to the relative positions of louvers shown in FIG. 1, i.e. the continuous channels 518 are of uniform width throughout the full length thereof. It is assumed that the source of light includes at least one elongated lamp which is located behind the grillwork and which extends horizontally, as viewed in FIG. 8, so that the louvers 513 517x enclose acute angles with the longitudinal direction of the lamp.

FIG. 9 illustrates a further modification of my invention according to which the planes of the corrugated mounted in the opening formed at the underside of a frame 610 forming part of a lighting unit B which comprises a light source including two elongated tubular lamps 611a, 6111) which are spaced from and are parallel with the general plane of the grillwork. By inclining the planes of the individual louvers with respect to the general plane of the grillwork, the manufacturer can produce different lighting effects, i.e. the light rays may be deflected in a given direction. Of course, it will be readily understood that the lighting unit of my invention may comprise louvers which are in part inclined through acute angles (FIG. 9) and which are in part perpendicular (FIGS. 1-8) to the general plane of the grillwork.

As stated before, the spacing between the adjacent louvers (i.e. the width of the continuous channels defined by the louvers), the width of the louvers (i.e. the height, as viewed in FIGS. 2, 3 or 9), the distance between the light source and an observer, and/or the dimensions of the light source will determine the angles at which the light source is fully concealed from an observers eye. The selection of the above values depends on the judgment of the illuminating engineer and on certain other factors, such as the dimensions of and the furnishings in the area which requires illumination.v

The word corrugated, as utilized in the appended claims, is intended to denote louvers or strips of undulate, zig-zag, trapeziform or any similar shape which deviates from a straight line and which may be obtained by bending adjacent sections of the strips in opposite directions.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications Without omitting features that from the standpoint of prior art, fairly constitute essential characteristics of the generic and specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be protected by Letters Patent is:

1. A lighting unit comprising, in combination, a source of light located above a surface to be illuminated; a frame for said source; and a grillwork in said frame beneath said source for modifying the distribution of light emanating from said source, said grillwork being disposed in a substantially horizontal plane and comprising a plurality of undulate louvers having ends cormected to said frame and defining between themselves a plurality of continuous downwardly open undulate channels for the passage of light rays through said grillwork, said channels being of substantially uniform width throughout the full length thereof and said grillwork constituting the sole barrier between said source and the eye of an observer so that each of said channels is accessible at all times from the underside of the grillwork to facilitate cleaning of the louvers.

2. A lighting unit as set forth in claim 1, wherein said frame is of substantially rectangular shape and wherein said louvers extend substantially diagonally of the frame.

3. A lighting unit as set forth in claim 1, wherein said louvers resemble undamped sine waves.

4. A lighting unit as set forth in claim 3, wherein each louver comprises a plurality of crests and troughs and wherein the crests and the troughs of adjacent louvers are disposed in common planes.

5. A lighting unit as set forth in claim 3, wherein each of said louvers comprises a plurality of crests and troughs, the crests and troughs of each louver being respectively disposed in common planes and the crests of each louver extending through the common plane of the troughs of an adjacent louver.

References Cited in the file of this patent UNITED STATES PATENTS 1,219,389 Griggs Mar. 13, 1917 1,430,390 Lodge Sept. 26, 1922 1,654,666 Ross Jan. 3, 1928 2,756,325 Zwick July 24, 1956 FOREIGN PATENTS 285,419 Great Britain May 24, 1928 633,090 Great Britain Dec. 12, 1949 715,493 France Sept. 28, 1931 562,399 Italy May 9, 1957 

1. A LIGHTING UNIT COMPRISING, IN COMBINATION, A SOURCE OF LIGHT LOCATED ABOVE A SURFACE TO BE ILLUMINATED; A FRAME FOR SAID SOURCE; AND A GRILLWORK IN SAID FRAME BENEATH SAID SOURCE FOR MODIFYING THE DISTRIBUTION OF LIGHT EMANATING FROM SAID SOURCE, SAID GRILLWORK BEING DISPOSED IN A SUBSTANTIALLY HORIZONTAL PLANE AND COMPRISING A PLURALITY OF UNDULATE LOUVERS HAVING ENDS CONNECTED TO SAID FRAME AND DEFINING BETWEEN THEMSELVES A PLURALITY OF CONTINUOUS DOWNWARDLY OPEN UNDULATE CHANNELS FOR THE PASSAGE OF LIGHT RAYS THROUGH SAID GRILLWORK, SAID CHANNELS BEING OF SUBSTANTIALLY UNIFORM WIDTH THROUGHOUT THE FULL LENGHTH THEREOF AND SAID GRILLWORK CONSTITUTING THE SOLE BARRIER BETWEEN SAID SOURCE AND THE EYE OF AN OBSERVER SO THAT EACH OF SAID CHANNELS IS ACCESSIBLE AT ALL TIMES FROM THE UNDERSIDE OF THE GRILLWORK TO FACILITATE CLEANING OF THE LOUVERS. 